Various applications exist where particulate material is discharged from a gravitationally bottom mouth of a holding reservoir or like vessel. There are often problems in achieving a uniform discharge of material over a desired time interval or at desired time intervals from such a mouth. Commonly, in the prior art, a discharge-facilitating device, such as a vibrator or animal actuatable wand shaking means, is associated with the mouth.
In, for example, fish feeding apparatus of the type shown in Sweeney U.S. Pat. No. 4,565,159, a hopper-like reservoir holds particulate fish feed which is discharged from a bottom mouth of the reservoir onto a water surface for consumption by fish in the water. The bottom mouth is partially closed by a cover plate so that only a small spacing is defined between the side edges of the bottom mouth and the cover plate. Elongated bolt and nut means interconnect the reservoir sides with the cover plate. A bottom central region of the cover plate is associated with an electrically actuatable vibrator means. When the vibrator means is actuated, the cover plate and the reservoir sides vibrate. The relationship between the small spacing and the vibration is adjusted so that, during vibration, fish feed is dispensed from the reservoir through the small spacing and onto the underlying adjacent water surface.
Unfortunately, the Sweeney apparatus suffers from various disadvantages. One disadvantage is that, particularly when the volume of the reservoir is relatively large and is largely filled with fish feed, there is a tendency for the fish feed to bridge and hang-up over and in the vicinity of the small spacing. Resultingly, when the cover plate vibrates, either no fish feed is dispensed, or fish feed is dispensed irregularly or non-uniformly through the small spacing.
Another disadvantages is that, even when the vibrator mean after actuation operates at a constant pattern or frequency, dispensing of fish feed from the reservoir through the small spacing can occur at different rates. The dispensing rate at a given time is related to the fill level of fish feed in the reservoir particularly when the reservoir is sufficiently large to be practical in commercial scale aquaculture. Typically, when material bridging or hang-up does not occur, the greater the height (or weight) of fish feed in the reservoir, the less the quantity of fish feed that is dispensed through the small spacing during an interval of vibration. Perhaps this result is associated with an impairment in, or a dampening of, the effective vibration due to the overbearing weight of the fish feed in the associated well-filled reservoir.
Another disadvantage is that, even though, as taught by Sweeney '159, the Sweeney '159 apparatus in a small-sized embodiment may achieve during vibration regulated dispensing of very fine feeds having a high oil content (such as may be used with small young animals), as one employs larger embodiments of Sweeney '159 apparatus, and feeds of larger particle size, such as pelletized feeds (such as may be used with relatively large animals), one loses the capacity to regulate the particular amount of feed released during individual periods of vibration.
The aquaculture of fish, particularly in high fish density culture systems, requires control of water quality, and adequate, regular and uniform fish feeding, to achieve a maximized but controlled rate of fish growth. Insufficient feeding results in slow or abnormal fish development. Excessive feeding results not only in incomplete feed consumption by the fish even when the feed is ingested by the fish, but also in water contamination problems. Irregular feeding caused by progressive or cyclical changes in feed rates, such as can occur when in operation the fish feed reservoir associated with of a Sweeney '159-type feed dispensing device is gradually emptied of feed and then is abruptly refilled, can adversely affect water quality and cause water contamination problems that are adverse to fish culture.
The above indicated Sweeney '159-type fish feeding apparatus does not provide adequate control of fish feeding, particularly under high density culture conditions, especially when using a fish feed reservoir or feeding apparatus of practical, relatively large volumetric capacity.
The art of aquaculture needs improved apparatus for dispensing fish feed which overcomes such disadvantages.